The paper looks at the possible hit to GDP over the next decade-and-a-half from Britain leaving the EU, compared with the UK remaining full members of the bloc.

Overall, the UK is predicted to suffer a 1.5% drop in GDP while remaining in the EU's single market via the European Economic Area (EEA), a 5% drop if it agrees a free trade deal, and an 8% drop if Britain leaves the EU without a deal and reverts to trading on World Trade Organisation terms.

It comes as a key Cabinet sub-committee tries to establish a common position on the next phase of Brexit negotiations, with top ministers due to discuss the Northern Ireland border on Wednesday.

Earlier, in the House of Commons, an MP appeared to confirm the estimated 12% hit to GDP in Northern Ireland in the event of a no-deal Brexit.

Image:Stephen Gethins asked about the Government's own analysis

The SNP's Europe spokesperson, Stephen Gethins, asked Northern Ireland Secretary Karen Bradley: "The Scottish Government analysis has shown that a 'no-deal' scenario could cost Scotland up to 8.5% of GDP.

"Government analysis suggests that Northern Ireland could be cost up to 12% of its GDP.

"Does she believe any analysis she has seen? And is this too high a price to pay to stop a Tory civil war breaking out?"

In response, Mrs Bradley said Brexit Secretary David Davis had "dealt with the issues surrounding the leaked report".

"It is important to state that the UK Government wants to achieve a good deal for the UK that protects the economic integrity of the UK," she added.

The initial leak of the analysis, to website BuzzFeed, sparked claims from Tory Brexiteer Jacob Rees-Mogg that civil servants were "fiddling the figures" in order to influence Brexit policy.

Image:Karen Bradley said the Government wants a 'good deal' for the UK

The Government has distanced itself from the "provisional internal analysis", which MPs have now been allowed to read in full on a confidential basis.

A spokesperson said: "This document does not represent Government policy and does not consider the outcome we are seeking in the negotiations.

"As Ministers clearly set out in the House of Commons, this is provisional internal analysis, part of a broad ongoing programme of analysis, and further work is in progress.

"We are seeking an unprecedented, comprehensive and ambitious economic partnership - one that works for all parts of the UK.

"We are not expecting a no deal scenario."

In response to the full regional breakdown, Labour's shadow Brexit minister Paul Blomfield said: "These figures are further evidence of why the Tories must rethink their reckless approach to the Brexit negotiations.

"The final Brexit deal with the EU must work for every region and nation of the UK, protecting people's jobs and local economies.

"That is why Labour has been clear from the outset that the Government should seek a deal that retains the economic benefits of our current membership with the EU.

"Options for achieving that should not have been swept off the negotiating table, including being in a customs union with our largest trading partner."